Microtubules and actin microfilaments in the amphibian bladder granular cells.

Microtubules and microfilaments were localized by an immunocytochemical method in the granular cells of the frog bladder after fixation and isolation. An extensive array of microtubules was observed in the granular cells with an orientation towards the luminal plasma membrane in the supranuclear zone. Actin filaments formed a continuous bundle that underlined the cellular membrane. After incubation in the presence of colchicine, nocodazole, or tubulozole, the microtubular network appeared fragmented but did not disappear completely. These observations are related to the role of the cytoskeleton in the permeability response of the frog bladder epithelium to vasopressin.